I'm a sighted user and just wondering how keyboard-only users navigate through a page.
Here is the page that raised the question: http://www.governor.wa.gov/ . Is there a way to tab into the sub menus that are exposed when mousing over the top nav items?

Also, there are blocks of content on the page and each has its own heading. However, if I tabbed to get to the Twitter block of content, how do I easily get out of it if I'm a keyboard only user? I wouldn't want to have to tab through every tweet to move onto the next block which contains the Facebook posts.

Are there any resources you might refer me to to learn more about how keyboard-only users interact with pages?